What standards do internal auditors use?

Whilst ISO 19011 is not mandatory, it is recommended that auditors align to this guidance where appropriate to the specific needs and requirements of their audit programme.  Additional standards relevant to ISO 27001 may also be used when auditing individual elements of your ISMS:

• ISO 27007:2020 provides guidance on ISMS auditing and concentrates on Clauses 4-10 of the Standard
• ISO 27008:2019 provides guidance for the assessment of information security controls (Annex A of the Standard).